Genetic Variation Of The Beta-2 Adrenergic Receptor Influences Power Output In Healthy Subjects: 124 June 1, 10: 15 AM - 10: 30 AM

BACKGROUND: Muscular strength and power are important in health, disease, and with aging. With age and disease, a decrease in muscular strength and power are primary contributors to a drop in functional capacity. The beta-2 adrenergic receptors (ADRB2) are important in muscle growth and power output through increased size and glucogenolysis. In disease models, the ADRB2 have been shown to be important in Ca super(+) homeostasis and cAMP accumulation in cells, both of which are important in attenuating the deterioration of muscle cell function. PURPOSE: The purpose of this study was to determine the effects of ADRB2 genotypes on muscle function (absolute power and relative power) in healthy subjects. METHODS: To determine this, we performed genotyping of the ADRB2 (amino acid 16) and maximal exercise on 77 healthy subjects (AA = 18, AG = 25, GG = 34). RESULTS: There were no differences between genotype groups in age, height, weight, or BMI (age = 28.9 + or - 5.7yrs, 27.9 + or - 5.7yrs, 29.2 + or - 5.9yrs, height = 170.7 + or - 8.6cm, 174.9 + or - 8.7cm, 173.4 + or - 9.6cm, weight = 68.5 + or - 13.0kg, 75.0 + or - 12.9kg, 74.4 + or - 12.9kg, and BMI = 23.4 + or - 3.9, 24.4 + or - 2.9, 24.7 + or - 3.4, for AA, AG, and GG, respectively). The genotype groups differed significantly in watts, and watts/VO sub(2) at peak exercise with a trend towards significance (p=0.058) for watts/kg (watts = 186.3+ or - 54.6, 237.8 + or - 54.4, 219.4 + or - 79.5, watts/VO2 = 0.08 + or - 0.006, 0.09 + or - 0.005, 0.08 + or - 0.006, and watts/kg = 2.7 + or - 0.4, 3.2 + or - 0.5, 2.9 + or - 0.8, for AA, AG, and GG, respectively). CONCLUSION: These data suggest that genetic variation of the ADRB2 may influence relative strength in healthy subjects and may become an important genetic determinant of muscular strength and functional capacity in patients with diseases that result in a loss of muscle strength.